a. Field of the Invention
This invention pertains to feed systems for microwave reflector antennas. More particularly this invention pertains to feeds for microwave reflector antennas used for communicating with commercial earth satellites.
b. Description of the Prior Art
Commercial earth satellites, such as the DBS and Echostar satellites, are being used to broadcast television signals direct to consumers. One type of antenna system used by the consumer for receiving the television signals includes a reflecting dish in the form of an offset parabolic reflector that is fed by a waveguide horn or open-ended waveguide with associated chokes. These systems operate at Ku band, i.e. in a frequency band centered at approximately 12.5 ghz.
Commercial earth satellites now also provide a means for telephonic communications direct to consumers using circularly polarized radio waves in the L band frequency range, i.e. in a frequency band centered at approximately 1.5 ghz. Certain of the earth satellites that are used for the broadcasting of television signals direct to the consumer and certain of the earth satellites that provide the telephonic communications are located very close to each other as viewed by the consumer from the surface of the earth. In the prior art, completely separate antenna systems were used to provide reception of such direct broadcast television signals and to provide telephonic communications.